266 Mr. C. F. M. Swynnerton on the 



can carry bright colour always exposed. The procryptic 

 mantle is retained in these cases till detection becomes 

 inevitable. Then it is dropped, and the hidden coloration 

 revealed as a vivid last appeal to the enemy's memory. 

 The young bird's mouth-colours when he opens his bill to 

 an approacherj the coloration of the eggs when the nest is 

 looked into, a butterfly's upper surface during motion, 

 displays by animals fleeing or at bay, illustrate the principle. 



Warning Coloration. — Originally his suggestion to Darwin 

 in explanation of the " splendid " coloration of certain 

 caterpillars, Wallace soon extended the idea of " warning " 

 to the colours of numerous other animals, terrestrial and 

 marine. " The animals in question are either the possessors 

 of some deadly weapons, as stings or poison-fangs, or 

 they are uneatable, and are thus so disagreeable to the 

 usual enemies of their kind, that they are never attacked 



when their peculiar powers or properties are known 



They require [however] some signal or danger-flag which 

 shall serve as a warning to would-be enemies not to attack 

 them, and they have usually obtained this in the form of 

 conspicuous or brilliant coloration."* " Thus the most 

 gaudy colours would be serviceable and might have been 

 gained by variation and the survival of the most easily- 

 recognised individuals " (Darwin, ' The Descent of Man,' 

 1901 ed. p. 499). 



"Deadliness" and absolute "inedibility" are rare quali- 

 ties even in the unpleasantest of prey, and (as Prof. Poulton's 

 experiments on the lizard, P hrynocephalus mystaceus, first 

 indicated) the latter enjoys only a relative immunity from 

 attack even when known, for the digestive secretions of a 

 really hungry enemy can, and do, conquer much. Other 

 modifications, too, can be suggested, but the principle of 

 " warning " stands, backed now by much evidence. 



The keen study of insect coloration that has taken place 



under Prof. Poulton's inspiring leadership, has secured an 



ample recognition of that principle by entomologists, and 



Mr. R. I. Pocock has made some very interesting suggestions 



* Wallace, ' Darwinism,' p. 232. 



